Iron ore smelting pig iron, how to refine iron from iron ore

The main methods for extracting iron from iron ore are blast furnace method, direct reduction method, melt reduction method and plasma method. Among them, blast furnace ironmaking is to send iron ore, coke, carbon monoxide, hydrogen and other fuels and fluxes to the blast furnace for smelting in batches by the furnace top charging device according to the specified batching ratio, and remove impurities to obtain metallic iron (pig iron).

The melt reduction method is a method of reducing the spoiled iron ore in a high-temperature molten state without using a blast furnace, and its product is liquid molten iron with a similar composition to the blast furnace molten iron.

Ironmaking is the process of refining metallic iron from iron-bearing minerals. From a metallurgical point of view, ironmaking is the reverse of iron rusting and gradual mineralization, that is, the reduction of pure iron from iron-containing compounds.

In actual production, pure iron does not exist, and what is obtained is an iron-carbon alloy.

The pig iron is further smelted in the steelmaking furnace, and enough oxygen is supplied, through the high-temperature oxidation in the furnace, part of the carbon core shed is oxidized into carbon monoxide gas and escapes, and other impurities are formed into oxides into the slag to remove, so that the carbon content can be reduced, so as to obtain a product with carbon content that meets the requirements, that is, steel, this process is called steelmaking.

Pig iron steelmaking refers to controlling the carbon content, generally less than two percent, eliminating harmful elements such as phosphorus, sulfur, oxygen leakage, nitrogen, etc., retaining or increasing manganese, chromium, nickel, and other beneficial elements and adjusting the ratio between the elements to obtain the best performance. At present, the commonly used steelmaking methods are: air conversion to virtual furnace method, oxygen converter method, open-hearth furnace method, and electric furnace method.

Construction steel is generally obtained by the first three methods.

1.Meaning of pig iron.

Pig iron refers to unrefined iron obtained directly from the ironmaking furnace and contains a large amount of impurities such as carbon, silicon, manganese, etc. Because pig iron has low hardness, strong brittleness, and insufficient strength, it cannot be used directly. Therefore, pure feast, pig iron needs to be further smelted and converted into steel before it can be utilized.

2.The meaning of steel.

Steel is an iron-carbon alloy with a carbon content of generally between. The qualitative characteristics of steel are high hardness, good ductility, strong wear resistance and good plasticity, so it is widely used in aviation, aerospace, automobile, construction, machinery, electric power, ships and many other fields.

3.The principle of pig iron smelting into steel.

In order to smelt pig iron into steel, it is necessary to carry out the process of carbon removal and other impurities. The carbon content of pig iron is as high as 4% to 5%, and the carbon content is different for different steels for different purposes. Therefore, in order to meet the requirements, adjustments need to be made.

The pig iron produced by the blast furnace is removed after pretreatment such as quenching and tempering, stir-frying, etc., including molten iron, iron slag and exhaust gas. Iron elements and ferroalloys in pig iron are the main raw materials for making steel, and carbon removers are one of the main materials to control the composition of steel.

There are two main parts of the smelting process, namely, the reduction of carbon and the physicochemical action of the melt flow. The carbon reduction process can reduce the carbon content in pig iron, while the melt flow physicochemical action can cause orderly changes in various elements in pig iron, and realize the adjustment of composition and properties.

4.Ways to remove carbon.

There are several ways to remove carbon. We can use basic oxides, which are added directly to molten iron. Since alkalinity neutralizes acidity, elements such as silicon, manganese, and phosphorus in iron can also be combined with cations to form corresponding oxides.

When a decarburizer is added to molten iron, iron oxide in steel is not formed because it is reduced to components such as elemental iron, ferroalloys, carbides, etc. The mode of reaction and chemical equilibrium in the process can be understood using the fundamentals of thermodynamics and kinetics.

5.The principle of smelting.

The principle of smelting is to melt pig iron and other additives at extremely high temperatures, so that the carbon and other elements in the pig iron undergo a decomposition reaction to carry the pants, so as to achieve the purpose of turning pig iron into steel.

In smelting, we not only need to master the temperature adjustment, but also need to reasonably control the feeding method and the amount added to ensure the composition and quality of steel.

6.Precautions in the smelting process.

In the process of pig iron smelting, the following issues need to be paid attention to.

1.Adjustment of temperature. When heating, the temperature and speed should be adjusted accordingly to ensure that the chemical reaction of every element used in the steel is able to be completed. At the same time, when the melting point is not reached, we need to control the furnace fire to ensure that the temperature is not too positive.

2.Replenishment of raw materials. In steel smelting, different raw materials are often required, and supplementing the wrong raw materials can lead to changes in the data during processing.

7.Epilogue.

The process of smelting pig iron into steel is very complex, the main process is carbon reduction and smelting, and some issues need to be paid attention to in order to ensure the performance and durability of steel to meet the production needs of various fields.